Ch. 16 Textbook Review Questions

Question 1

Explain how ocean acidification is likely to affect molluscs. Describe the long term effects of this process to human economies

Answer 1

As the pH lowers, it becomes more difficult for calcium shells and skeletons to form. Calcium is critical for mollusk shells. This will affect human economy in the long term because mollusks are an extremely important food source.

Question 2

What characterisitcs of Mollusca distinguish it from other phyla

Answer 2

-Muscular foot
-Visceral mass
-Mantle

Question 3

Briefly describe the habitat and habitats of a typical chiton

Answer 3

Rocky intertidal surfaces,

Question 4

What is torsion and what functional
problem results from torsion? How have gastropods evolved to avoid this problem

Answer 4

Torsion- changes the relative position of shell, digestive tract, anus (moves from posterior to right side above head, mantle cavity (gives space to withdraw head)

Problem-sanitation fouling

adaptations- by losing the gill, made it possible to avoid fouling because water is now brought into the left side of the mantle cavity not the right, carrying with it the waste. No organs on the right, so no harm no foul.

Question 5

Describe how cephalopods feed and how they swim by jet propulsion

Answer 5

The use of there tentacles to grab prey
expel water thru siphons
lateral fins
crawl backwards

Question 6

Describe the adaptations in the circulatory and neurosensory systems of cephalopods that are particularly valuable for actively swimming, predaceous animals

Answer 6

Circulatory- muscles circulate water thru mantle cavity to bring in oxygen, closed network of vessels

Neurosensory- cephalopod brain, well-developed sense organs
learn by reward/punishment
bioluminescent-secrete sepia (ink)

Chromatophores- change color bc of skin cells containing pigment granules

Question 7

Distinguish b/t ammonoids and nautiloids

Answer 7

ammonoids- extinct by end of Cretaceous for unknown reasons

Nautiloids- only living cephalopod w/ external shell
shell divides into chambers

Question 8

Briefly describe how a typical bivalve feeds and how it burrows

Answer 8

Bivalve gills were modified for filter-feeding
Use their foot to burrow

Question 9

Describe how a shell is made and explain how the mantle is exploited to produce a pearl

Answer 9

Shell- slowly secretes layers of aragonite and conchiolin, materials that also make up its shell

Pearls result from irritant b/t shell and mantle layers of nacre secrete around it